Working with certain types of granular material can pose significant health risks. According to the U.S. Occupational Safety & Health Administration (“OSHA”), inhalation of small crystalline silica particles puts workers at risk for silicosis, lung cancer, chronic obstructive pulmonary disease, as well as liver, heart, and kidney disease. With the increase of hydraulic fracturing (“fracking”) over the past 5-10 years, the instances of sicknesses and deaths due to silica inhalation have rapidly increased. Many fracking sites fail to meet current OSHA standards. Moreover, OSHA has proposed a new rule lowering the permissible exposure limit of respirable crystalline silica per cubic meter of air. This lower limit will impact almost any industry that involves transporting or otherwise using silica.
Fracking is a process for stimulating an oil well by fracturing underground rock using a pressurized liquid. The pressurized liquid consists primarily of water mixed with a proppant. A typical proppant is sand, such as “frac sand,” although other granular materials can be used as well. The proppant functions to maintain an induced hydraulic fracture open such that the desired oil or gas can be extracted. A single fracking well can require several thousand tons of frac sand.
Frac sand is mined and processed in a plant to improve its performance characteristics. The sand then gets transported from the plant to the fracking site. This transportation process can involve trains, ships, trucks, conveyors, and other transportation methods. Pneumatic pipe systems and conveyors are routinely used to transport sand from one container to another—for example, from a rail car to a truck or from a truck to a storage facility. Pneumatic and conveyor transfers allow silica particles to permeate the air in the surrounding area, causing a potential health hazard to any workers nearby.
In addition to the health hazards, the typical processes for transporting frac sand have additional drawbacks. For example, a container (e.g., a rail car or a truck) designed to hold frac sand may not be useful for carrying other items. That is, once the load of frac sand has been deposited, the rail car or container cannot be used for another purpose; instead, it must be returned to a location where it can be refilled with frac sand. The lack of reusability increases transportation costs and, as a result, the overall cost of fracking.
Therefore, a need exists for systems and methods for safely and efficiently transporting granular material. More specifically, a need exists for systems and methods for transporting granular material in a manner that limits respirable silica emissions, eliminates harmful pneumatic transfers, and provides lower transport costs.